1. Field of the Invention
The present invention relates to a ultrasonic-welding apparatus which can measure the face-deflection of work pieces, such as a reel joined by the ultrasonic-welding, and an optical sensor for ultrasonic-welding apparatus, a rotation sensor for ultrasonic-welding apparatus, and a location controlling method of the optical sensor for ultrasonic-welding apparatus.
2. Prior Art
Generally, a reel, onto which a magnetic tape is wound, is stored in the magnetic tape cartridge, which is used as recording medium such as a computer and videotape. The reel is formed by welding a reel hub and one flange together using the ultrasonic-welding apparatus. The reel hub is composed of a shaft, onto which a magnetic tape is wound, and other flange which are united together into an integral body.
Since the flange of the reel functions as a guide for winding a magnetic tape with sufficient accuracy, the parallelism between one flange and the flange of another side needs to be achieved with extreme precision. For example, in the case of the reel with a diameter of 100 mm, the face-deflection of a flange must be achieved within 0.18 mm. When the deflection of the dimension between both flanges is large, the problems, such as the imperfect winding, damaging on the edge of a magnetic tape, poor recording, and the tape jamming, may occurred.
Conventionally, the face-deflection of the flange of another side (located at the welded side) was measured along the following manner, specifically, after welding the flange of the another and the reel hub together by the ultrasonic-welding apparatus, the reel after welding is moved to the cradle from the welding apparatus for measurement. Then, the height of the top face of the flange of another side is measured with a dial gage on rotating the cradle. The distance between both flanges had been measured by the man power using a micrometer and the like. After recording the measured data on paper, these data were further inputted into a computer.
Since above described measurement works are carried by man power, great number of man-hours had been needed. Thus, two workers and much tact-time were required at each manufacturing line of reel. Since the measured data was inputted into a computer after once recording the measured data on paper, the operation of such works were complicated and there was also fear of the incorrect recording by posting or input mistake. Furthermore, the measuring apparatus of a face-deflection needed to be placed apart from the ultrasonic-welding apparatus, and the working space for the measuring apparatus is also required.
Therefore, automation of these measurement works has been desired. Still more preferably, it have been desired that the ultrasonic-welding apparatus which can continuously perform the operations from the welding to the face-deflection measurement of the work pieces on the condition where the work piece, such as reel, is mounted on the ultrasonic-welding apparatus.
Meanwhile, in order to measure the face-deflection of the work piece after welding with accuracy, the detection of the location of a work piece is required. For achieving this detection, an optical sensor, such as a transmission-type laser sensor, may be used.
Generally, an optical sensor is composed of a light-emitting device and a light-receiving device. When arranging the optical sensor on the cradle for the face-deflection measurement, the location of the light-emitting device and the light-receiving device is determined at both sides of the reel so that the reel is located between the light-emitting device and the light-receiving device. That is, location of the light-emitting device and the light-receiving device is determined so that the run direction of the laser light and the central axis of the light-receiving image should become parallel and perpendicular to the receiving surface of the cradle, respectively.
When the laser light is emitted from the light-emitting device to the region, where the one flange and the another flange of the reel are contained, while the cradle onto which the reel is mounted is rotating, the flange part of the light-receiving image becomes shade. The face-deflection of the reel thus will be detected by checking the change of the shade of the light-receiving image in the perimeter of the reel.
In the conventional optical sensor arranged on the cradle for the face-deflection measurement, however, the location of the light-emitting device and the light-receiving device was not adjusted after arrangement. When the optical sensor is simply arranged on the ultrasonic-welding apparatus for automating the operation from the welding to the face-deflection measurement, therefore, the displacement of the location of the light-emitting device and the light-receiving device may be caused by the vibration of the ultrasonic-welding apparatus.
As a result of the displacement of the location, the run direction of the laser light becomes less parallel to the receptacle side of the cradle. The central axis of the light-receiving image becomes less perpendicular to the receptacle side of the cradle. The physical relationship between the flange of the reel mounted on the cradle and the light-emitting device and/or the light-receiving device thus will be changed from the initial physical relationship of those.
Consequently, the displacement between the detected face-deflection, which is detected by the transmission-type laser sensor, and the actual face-deflection of the reel will be arisen, and the detection accuracy of the face-deflection of the reel thus will be dropped. Therefore, there has been required an optical sensor which does not cause such problems even if it is applied to the ultrasonic-welding apparatus, i.e., the optical sensor for an ultrasonic-welding apparatus.
Moreover, since a cover for preventing the dispersion of the noise accompanying the ultrasonic excitation or the dust under welding is arranged on the ultrasonic-welding apparatus so that the part related to the welding, the work piece, mounted on the cradle will be covered. Thus the visual checking whether or not the reel is rotating normally during face-deflection measurement cannot be carried out.
For checking the rotation of the reel in this case, the arrangement of the rotation sensors, such as a rotary encoder, is required. When the rotation sensor is arranged into the ultrasonic-welding apparatus, arrangement of the rotation sensor near the rotors, such as the reel, may be disturbed depending on the composition of the ultrasonic-welding apparatus. Furthermore, when a rotation sensor is arranged within the adverse environment, in which dust or the like is contained, such as inside of the ultrasonic-welding apparatus, the durability of the rotation sensor may be fallen.
Therefore, there has been required that the rotation sensor for ultrasonic-welding apparatus which can detect the rotation of the work piece even if the location of the rotation sensor is distant from the work pieces, that is, the location where does not affected by the environmental condition.